In recent years, much has been learned about the structural organization and regulation of the pathways of intermediary metabolism in the promastigote form of leishmania which lives in the intestinal tract of phlebotomine flies. Very little is known about the metabolism of the amastigote forms that live in the phagolysosome of human macrophages and cause leishmaniasis. It is now possible to grow the amastigote form of Leishmania mexicana pifanoi in axenic culture, and this opens the way to understanding its metabolism and to study the sequential changes that occur during differentiation from one form to the other. These studies will become an integral part of my research program at Duke University Medical Center and will lead to an ongoing collaboration between Dr. Opperdoes and myself.